When it was first introduced, many saw the 1 Series as the 2002 reincarnate or, more optimistically, as a successor to the E30 M3. Relatively light and with a shorter wheelbase, visions of a more flickable, tossable (and slightly more affordable) sport coupe had enthusiasts salivating at the prospects. Aftermarket tuners have been quick to jump on the 1 Series, particularly the 135i with its twin-turbo N54 engine.

German tuner Hamann has been re-configuring BMWs since 1985. The company’s first offering was a turbocharged E30 M3. Since then, Hamann has been known to offer styling kits that suited the attention-starved and they were rarely described as subtle. Within the past few years, Hamann expanded its coverage to other marques, including Ferrari, Bentley, Aston Martin, Jaguar, Lamborghini, Maserati, Mercedes, Porsche and others. And with this expansion, it seems as though the design department decided to tone things down, with styling mods that were better integrated and more tasteful.

This 135i features the full Hamann treatment, except for the ECU upgrade. The parts include a Competition front spoiler, rear-end panel with cutouts for a four-pipe exhaust system, the four-pipe Sport exhaust, lowering springs that feature a 50mm reduction in front and 25mm in back, aluminum pedals, aluminum handbrake handle, Hamann’s PG3 wheels, and carbon side-view mirror covers.

Hamann doesn’t offer an ECU flash for U.S.-spec cars so Norman Yung, owner of the official U.S. distributor, Hamann America, decided he’d test an innovative new ECU flashing tool from a company called Amberg Cypheror. The company offers a flash tool that connects directly to the car’s OBD-II port or ECU and downloads the engine’s map. The owner then takes that map and sends it over to Amberg Cypheror, which then reads it and makes the necessary tweaks. After the new map is done, the customer can upload it onto the flash tool and plug it back into the car. Because the customer now has the original map and the tuned map, he can alternate between stock and modified tunes and change them when they see fit, for example, before they go to the dealer for service. In addition to re-maps for BMW, Amberg Cypheror also offers re-maps for Mercedes, with Porsche maps also in the works.

I had the opportunity to drive the car before and after the ECU flash, and only someone devoid of senses couldn’t tell the difference. The N54 is well known for being a turbocharged engine that doesn’t feel like it’s turbocharged. Its power curves are as flat and linear as a dry lakebed, making it a paragon of endless torque at any rev. The Amberg Cypheror flash gave the engine voluptuous horsepower and torque curves without hurting the bottom end or drivability. Now it’s obviously a turbocharged engine, providing that neck-snapping surge you expect, with the juicy, peaking spike in the power curve coming shortly after 2000 rpm and not letting up until it nears redline. Amberg Cypheror claims its re-program is good for 360 whp or roughly 400 hp to the crank, which is on par with what other ECUs are putting out.

On the Bay Area’s infamous Skyline Drive, this 135i was in its natural habitat, carving up the switchbacks and annihilating the straights. Before the ECU flash, I marveled at the engine’s flexibility. After the flash, I marveled at the transformation. The bump in power required an extra bit of caution to be added to the equation, that good kind of fear that keeps you on your toes and has you lifting a little earlier before braking for the corner.

Stuffed with wide tires (Toyo Proxes 225/35-19 front and 255/30-19 rear), it will cling to turns with mad levels of grip. Hunkered down and tightened up, body roll was barely perceptible. The brakes are stock and they didn’t fade on either of the two runs we made. All in all, it’s the rocket that it seems to be on paper. Less weight plus more power in a smaller package adds up to a car that can hold its own against more powerful and costlier competition.

The official 1 Series M will reportedly pump out 360 hp to the crankless than what you can do by flashing an N54’s ECU. Those who buy the factory version probably want the M logos and factory stylistic touches. But those who build their own won’t be missing out on anything.